With recent development of information communication technology, a variety of wireless communication technologies have been developed. From among them, WLAN is a technology that allows wireless access to the Internet at home, in businesses, or in specific service providing areas using mobile terminals, such as a personal digital assistant (PDA), a laptop computer, and a portable multimedia player (PMP), based on the radio frequency technology.
In order to overcome the limited communication speed, which has been pointed out as a weak point of WLAN, technical standards have recently introduced a system capable of increasing the speed and reliability of a network while extending a coverage region of a wireless network. For example, IEEE 802.11n supports high throughput (HT) with a maximum data processing speed greater than or equal to 540 Mbps. In addition, Multiple Input and Multiple Output (MIMO) technology, which employs multiple antennas for both a transmitter and a receiver in order to minimize transmission errors and to optimize a data rate.